This application is related to Japanese Patent Applications No. 2002-21544 filed on Jan. 30, 2002, and NO. 2002-329666 filed on Nov. 13, 2002, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a refrigerant cycle system having an ejector pump that is used as a refrigerant pump for performing a refrigerant transportation by a refrigerant flow jetted at a high speed.
2. Description of Related Art
In a conventional refrigerant cycle system described in JP-A-49-132739, an ejector pump, which is operated using a refrigerant flow heated by waste heat as a driving source, is provided. Further, a compressor and the ejector pump are combined, so that consumption power of the compressor is reduced. However, the conventional system has the following problems (1)-(5).
(1) In the conventional system, the compressor and the ejector pump are connected simply in series in a refrigerant flow. Therefore, when the refrigerant circulates only by the ejector pump and the operation of the compressor is unnecessary, a refrigerant flow resistance is increased in the compressor, and recovery heat cannot be effectively used.
(2) When the conventional system is applied to a vehicle air conditioner where a vehicle engine is used as an exhaust heat source of the system, an exhaust heat amount of the vehicle engine becomes larger sometimes in accordance with a vehicle travelling state. In this case, the above-described problem (1) may be caused. When the compressor is not provided in order to solve this problem (1), the refrigerant circulation cannot be performed only by the ejector pump when the exhaust heat amount from the vehicle engine is small.
(3) In the conventional system, R114 or R12 is used as the refrigerant. However, there is not described any regarding a super-critical refrigerant cycle where the pressure of the refrigerant flowing into the ejector pump becomes higher than the critical pressure of the refrigerant.
(4) In the conventional system, because refrigerant flowing into an evaporator is decompressed and expanded in iso-enthalpy, the energy loss in the decompression and expansion cannot be recovered, and operation efficiency is reduced.
(5) In an electrical vehicle such as a hybrid vehicle and a fuel cell vehicle, it is necessary to cool a battery mounted on a vehicle. However, in the conventional system, there is not described any regarding an application to an electrical vehicle.
In view of the foregoing problems, it is the object of the present invention to provide a refrigerant cycle system with an ejector pump, which solves at least one of the above-described problems (1)-(5).
According to the present invention, a refrigerant cycle system includes an evaporator that has a cooling capacity by evaporating refrigerant therein, a radiator for cooling refrigerant flowing from the evaporator, an ejector pump including a nozzle and being disposed to suck refrigerant from a side of the evaporator and to discharge the sucked refrigerant toward the radiator by a refrigerant stream jetted from the nozzle, a compressor disposed to suck refrigerant from the side of the evaporator and to discharge the sucked refrigerant toward the radiator, and a heating unit for heating refrigerant to be introduced into the nozzle. In the refrigerant cycle system, the ejector pump and the compressor are disposed to select any one of a first mode where refrigerant circulates from the evaporator toward the radiator only by the ejector pump, a second mode where refrigerant circulates from the evaporator toward the radiator only by the compressor, and a third mode where refrigerant circulates from the evaporator toward the radiator by both the ejector pump and the compressor. Accordingly, any one of the first mode, the second mode and the third mode can be selectively set based on a thermal load of the evaporator and the like. For example, when the operation of the compressor is unnecessary, the refrigerant circulates only by the operation of the ejector pump. Further, when a heating degree of the heating unit is small, both the compressor and the ejector pump are operated so that operation efficiency of the refrigerant cycle system can be improved. Further, when the heating unit heats the refrigerant using waste heat such as engine-cooling water (hot water) from a vehicle engine as a heating source, the waste heat in the vehicle engine can be effectively recovered while a refrigerant flow resistance can be effectively reduced in the refrigerant cycle system. In the refrigerant cycle system, the compressor and the ejector pump can be disposed in series or in parallel, relative to a refrigerant flow from the evaporator to the radiator.
Preferably, the refrigerant cycle system further includes a switching valve for opening and closing a bypass passage through which refrigerant from the evaporator flows toward the radiator while bypassing the compressor. Therefore, when the operation of the compressor is unnecessary, refrigerant bypasses the compressor, and it can prevent the refrigerant flow resistance from being increased in the compressor.
In the refrigerant cycle system, the pressure the refrigerant flowing from the heating unit to the nozzle of the ejector pump can be set to be equal to or higher than the critical pressure of the refrigerant. In this case, the operation efficiency of the ejector pump can be effectively improved.
In the refrigerant cycle system of the present invention, the evaporator can be disposed to cool air to be blown into a compartment, for cooling the compartment. Alternatively, the evaporator can be disposed to cool a heat-generating member that generates heat when being operated. The heat-generating member can be a battery mounted on a vehicle.
According to the present invention, a refrigerant cycle system includes a first ejector pump and a second ejector pump. The first ejector pump includes a nozzle for converting a pressure energy of refrigerant to a speed energy thereof so that the refrigerant is decompressed and expanded, and is disposed to suck refrigerant from a side of the evaporator and to discharge the sucked refrigerant toward the radiator by a refrigerant stream jetted from the nozzle. On the other hand, the second ejector pump includes a nozzle for converting a pressure energy of refrigerant to a speed energy thereof so that the refrigerant flowing from the radiator toward the evaporator is decompressed and expanded, and a pressure-increasing portion in which the speed energy is converted to the pressure energy so that the pressure of refrigerant to be discharged is increased while refrigerant jetted from the nozzle and refrigerant sucked from the evaporator are mixed. Accordingly, energy loss in decompression and expansion can be effectively recovered, and operation efficiency can be further effectively improved.
According to the present invention, in a refrigerant cycle system, a gas refrigerant supplying unit is disposed for supplying gas refrigerant branched from the radiator to the heating unit. Therefore, it is unnecessary to use the waste heat for boiling and evaporating refrigerant in the heating unit, and large amount of heat can be recovered for performing pumping operation. Thus, the efficiency of the refrigerant cycle system can be effectively improved. Here, the gas refrigerant supplying unit can be constructed by a gas-liquid separator for separating refrigerant into gas refrigerant and liquid refrigerant, and a compressor for press-sending gas refrigerant supplied from the gas-liquid separator to the heating unit. Further, the radiator can include a first radiator and a second radiator which are connected through a refrigerant passage. In this case, the gas-liquid separator is connected to the refrigerant passage between the first radiator and the second radiator.